mommy of 2 needs to loose weight

hi i wanted some advice and opinions on how i could loose weight without the pills and all that other junk. im 19 and have 2 kids and currently breastfeeding my youngest son. im 4'9 and currently weigh 139 lb, im not sure how much i should weigh but i have seen charts online showing how much one should weigh based on height and according to the chart i should weigh 120lb im not sure if thats accurate but i think i should be in the 125 range. my husband has given me a motive to get me going and its working he gives me 6 months to shed some weight in return for the puppy i've always wanted. i have been wanting to get back in shape for the longest now but i give up to easy and hopefully this puppy motivation helps me. please help me find a healthy way to shed some weight.